The present invention relates to a cooling system for high power internal combustion engines, and more particularly, to a unified rotary flow control valve for use in a cooling system used in a diesel engine powered rail traction vehicle.
Cooling systems for internal combustion engines, such as diesel engines used in locomotives and off highway vehicles, are known in the art for the purpose of maintaining engine and lubricating oil temperatures within desired operating ranges. Turbocharged engines are also known to utilize cooling systems for conditioning the combustion inlet air after it is compressed in a turbocharger. For example, it is believed that U.S. Pat. No. 5,415,147 (xe2x80x9cthe ""147 patentxe2x80x9d), assigned to the assignee of the present invention, describes a temperature regulating system containing turbocharged internal combustion engine having one coolant fluid pump and one or more flow paths where coolant fluid may be directed depending on the engine operating conditions. The temperature regulating system of the ""147 patent defines three modes of operation as follows:
Mode 1: Used when coolant temperatures are highest, such as when the engine is at the highest power levels and/or when the highest ambient air temperatures are encountered. Entire hot coolant outflow from the engine is directed to the radiator/subcooler. Coolant passing through the subcooler is used to cool the engine intake air in the intercooler.
Mode 2: Used when engine coolant temperature is high enough to warrant cooling but heating of the intake air is desired to obtain optimal engine operation. The radiator/subcooler are used to cool only a portion of the hot coolant outflow from the engine. The remainder is used to heat the engine intake air in the intercooler.
Mode 3: Used when the heat demand on the engine is lowest, such as at low power loads and/or cold ambient air temperatures. None of the coolant outflow from the engine is cooled in the radiator, but some of this heated coolant is used to heat the engine intake air in the intercooler. The radiator and subcooler are drained in this mode.
Particular flow paths for each of the three Modes described above are disclosed in the ""147 patent along with the flow control system valve requirement that is required to implement this cooling flow control system. The flow control system includes a two position, three way xe2x80x9cT-portxe2x80x9d, rotary valve shafted to an external air powered actuator and an on-off butterfly type valve for drainage of a radiator inlet piping (collectively V1 as illustrated in Table 1), and a second two-position three-way xe2x80x9cL-portxe2x80x9d valve shafted to an external air powered actuator and its associated second on-off butterfly valve (collectively V2 as illustrated in Table 2) for drainage of the subcooler outlet piping. Table 1, provided below, illustrates the possible combination of valve positions for the three way valves, with the flow ports of the valves designated as A, B, and C. Three of the four combinations are used for implementing Modes 1, 2, and 3 described above, and the fourth combination is unused in the prior art embodiments. The abbreviations used in Table 1 are as follows: Eng is engine; W/T is water tank; I/C is intercooler; Rad is radiator; and S/C is subcooler.
U.S. Pat. No. 6,098,576 (hereinafter xe2x80x9cthe ""576 patentxe2x80x9d), assigned to the assignee of the present invention, provides for a lower lube oil temperature for given high temperature ambient air conditions in a diesel electric locomotive with an enhanced split cooling system. The ""576 patent extended the split cooling concept of the ""147 patent by including a turbo charger, an oil cooler and an oil subcooler. Like the ""147 patent, the ""576 patent included two valve assemblies that are used for coolant flow control. While the first valve assembly in the ""576 patent is essentially identical to that used in the ""147 (identified as V1 in Table 2), the second assembly is considerably more complex, having eight ports in the rotary valve instead of three (identified as V2 in Table 2). However, even though the ""576 patent has several benefits over the ""147 patent, the increase in components increases the costs of parts as well as the costs of assembling the cooling system and increases the costs of maintenance costs over the life of the system. Furthermore, the reliability of the cooling system is lessened because of a higher parts count.
Like the ""147 patent, in the ""576 patent four modes are possible but only three modes are utilized in practice. The modes are as follows:
Mode 1: A normal engine operating mode in which coolant is used for cooling and the entire outflow from the engine is passed to the radiator. A portion of the coolant from the radiators is returned to the coolant tank while another portion is passed to the lube oil subcoolers. A portion of the lube oil subcooler""s coolant outflow is sent to the lube oil cooler while another portion of the outflow is sent to the intercooler subcoolers and then to the intercoolers.
Mode 2: Used at lower operating temperatures than Mode 3, wherein said hot coolant outflow from the engine is used to heat the engine intake air in the intercooler, some is used to heat the engine lube oil in the lube oil cooler, and some coolant flows to the radiators and is returned to the coolant tank.
Mode 3: Used at start-up or in extremely cold weather when engine heat is needed to heat the engine intake air in the intercooler and to heat the engine lube oil in the lube oil cooler.
Particular flow paths for each of the three modes described above are disclosed in the ""576 patent along with the flow control system valve configuration requirement that is needed to implement this cooling flow control system. The flow control system includes a three way rotary valve shafted to an external air powered actuator and an on-off butterfly type valve for drainage of a radiator inlet piping, and a four-way rotary valve shafted to an external air powered actuator and an associated second on-off butterfly valve for drainage. Table 2, provided below, illustrates the possible combination of valve positions for the valves, with the actuators for the first valve labeled 1 and the second valve labeled 2, flow ports at the three-way valve assembly labeled A-C, and the flow ports at the four-way valve assembly labeled A-H. Three of the four combinations are used for implementing Modes 1, 2, and 3 described above, and the fourth combination is unused in the prior art embodiments.
A disadvantage of the prior art discussed above is the potential for coolant leaks. Having two rotary valves doubles the chance of a coolant leak since either valve can develop a leak. Still another disadvantage of the prior art discussed is the potential for air leaks. Pneumatic actuators with pressurized stem seals are often used to change valve positions. Having two rotary valves doubles the chance of air leaks since each rotary valve requires its own pneumatic actuator.
Thus there is a need for a cooling system for use with an internal combustion engine where only one valve and actuator are used. There is a need to reduce the cost of fabricating and assembling the cooling system. There is also a need to reduce the maintenance costs and improve the reliability of the system by reducing the number of components used in the cooling system. Another need exists for using a valve assembly that occupies a minimum physical space and when enlarged to regulate other fluids, continues to occupy a minimum physical space. Another need exists for a valve assembly that can be integrated into an existing engine without requiring additional space.
Towards these ends, there is a need for a system and method for a turbo-charged internal combustion engine for a locomotive or off highway vehicle where the system comprises a coolant storage tank having an inlet and an outlet, a coolant pump associated with the tank operable to circulate coolant through the system, an engine coolant jacket in heat transfer relationship with the engine having an inlet in fluid communication with the tank outlet and an outlet, a combustion air intercooler having an inlet, a radiator having an inlet and an outlet, and a single flow rotary control valve. The single flow rotary control valve is connected in fluid communication with the coolant jacket outlet, intercooler inlet, radiator inlet, radiator outlet, and the tank inlet. The single flow rotary control valve is controllable to operate in a plurality of flow connection modes for selectively regulating a flow of coolant throughout the jacket, intercooler, radiator and tank, and thus a temperature of said engine under varying engine operating and environmental conditions.
The system further comprises a liquid cooled turbo charger having an inlet in fluid communication with the tank outlet and an outlet, an intercooler subcooler having a coolant input and output, a lube oil cooler having a coolant input and output, and a lube oil subcooler having a coolant input and output. The single flow rotary control valve is further connected in fluid communication with the oil cooler inlet, lube oil subcooler output, intercooler subcooler inlet and intercooler subcooler output. The single flow rotary control valve is controllable to operate in a plurality of flow connection modes for selectively regulating a flow of coolant throughout the coolant jacket, turbo charger, intercooler, radiator, tank, oil cooler, oil subcooler, and intercooler subcooler and thus a temperature of the engine under varying engine operating and environmental conditions.